[pmg-devel] [PATCH pmg-api v2] utils: check if file changed before reusing its hash

[pmg-devel] [PATCH pmg-api v2] utils: check if file changed before reusing its hash

[Maximiliano Sandoval]

We cache the hash of this file, it makes sense to first check if the
file changed via `stat` and recompute the hash if needed.

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
---
 Differences from v1:
   - Dont add unnecesary variables or functions
   - Use hash slices

 src/PMG/Utils.pm | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/PMG/Utils.pm b/src/PMG/Utils.pm
index c19b31f..d9c9d2d 100644
--- a/src/PMG/Utils.pm
+++ b/src/PMG/Utils.pm
@@ -1353,14 +1353,22 @@ sub scan_journal_for_rbl_rejects {
 }
 
 my $hwaddress;
+my $hwaddress_st = {};
 
 sub get_hwaddress {
+    my $fn = '/etc/ssh/ssh_host_rsa_key.pub';
+    my $st = stat($fn);
 
-    return $hwaddress if defined ($hwaddress);
+    if (defined($hwaddress)
+	&& $hwaddress_st->{mtime} == $st->mtime
+	&& $hwaddress_st->{ino} == $st->ino
+	&& $hwaddress_st->{dev} == $st->dev) {
+	return $hwaddress;
+    }
 
-    my $fn = '/etc/ssh/ssh_host_rsa_key.pub';
     my $sshkey = PVE::Tools::file_get_contents($fn);
     $hwaddress = uc(Digest::MD5::md5_hex($sshkey));
+    $hwaddress_st->@{'mtime', 'ino', 'dev'} = ($st->mtime, $st->ino, $st->dev);
 
     return $hwaddress;
 }
-- 
2.39.2

[pmg-devel] applied: [PATCH pmg-api v2] utils: check if file changed before reusing its hash

[Stoiko Ivanov]

applied the patch - Thanks!

a follow-up that does a syslog on a rather visible level ('err'),
in case this actually changes while a system is running, as Thomas
suggested would still be appreciated though!


On Thu, 31 Aug 2023 16:41:13 +0200
Maximiliano Sandoval <m.sandoval@proxmox.com> wrote:

> We cache the hash of this file, it makes sense to first check if the
> file changed via `stat` and recompute the hash if needed.
> 
> Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
> ---
>  Differences from v1:
>    - Dont add unnecesary variables or functions
>    - Use hash slices
> 
>  src/PMG/Utils.pm | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/src/PMG/Utils.pm b/src/PMG/Utils.pm
> index c19b31f..d9c9d2d 100644
> --- a/src/PMG/Utils.pm
> +++ b/src/PMG/Utils.pm
> @@ -1353,14 +1353,22 @@ sub scan_journal_for_rbl_rejects {
>  }
>  
>  my $hwaddress;
> +my $hwaddress_st = {};
>  
>  sub get_hwaddress {
> +    my $fn = '/etc/ssh/ssh_host_rsa_key.pub';
> +    my $st = stat($fn);
>  
> -    return $hwaddress if defined ($hwaddress);
> +    if (defined($hwaddress)
> +	&& $hwaddress_st->{mtime} == $st->mtime
> +	&& $hwaddress_st->{ino} == $st->ino
> +	&& $hwaddress_st->{dev} == $st->dev) {
> +	return $hwaddress;
> +    }
>  
> -    my $fn = '/etc/ssh/ssh_host_rsa_key.pub';
>      my $sshkey = PVE::Tools::file_get_contents($fn);
>      $hwaddress = uc(Digest::MD5::md5_hex($sshkey));
> +    $hwaddress_st->@{'mtime', 'ino', 'dev'} = ($st->mtime, $st->ino, $st->dev);
>  
>      return $hwaddress;
>  }